The objective of this research is to identify in vitro correlates of tumorigenicity which characterize the phenotype of tumor cells, to use these endpoint assays in transformation studies, and to ascertain their role maintaining the tumor cell phenotype. Recently published results indicate that anchorage independent growth shows a consistent correlation with tumorigenicity of mouse epidermal cells. These epidermal cell lines are being characterized with respect to presence of epidermal specific cell surface antigen, quantitative measures of tumorigenicity, levels of plasminogen activator activity, serum density and adhesion dependence of growth, cell surface glycoconjugate profiles, and growth factor and promoter receptor levels.